#include <stdio.h>
#define ROWS 3
#define COLS 4

int sum2d(int rows, int cols, int arr[rows][cols]);

int main(void) {
    int i, j;
    int rs = 3;
    int cs = 10;
    int junk[ROWS][COLS] = {
        {2, 4, 6, 8},
        {3, 5, 7, 9},
        {12, 10, 8, 6}
    };

    int morejunk[ROWS-1][COLS+2] = {
        {20, 30, 40, 50, 60, 70},
        {5, 6, 7, 8, 9, 10}
    };

    int varr[rs][cs]; // VLA
    
    for (i = 0; i < rs; i++)
        for (j = 0; j < cs; j++)
            varr[i][j] = i * j + j;

    printf("3x4 array\n");
    printf("Sum of all elements = %d\n", sum2d(ROWS, COLS, junk));

    printf("2x6 array\n");
    printf("Sum of all elements = %d\n", sum2d(ROWS - 1, COLS + 2, morejunk));

    printf("3x10 VLA\n");
    printf("Sum of all elements = %d\n", sum2d(rs, cs, varr));

    return 0;
}

int sum2d(int rows, int cols, int arr[rows][cols]) {
    int i, j, t;
    t = 0;
    for (i = 0; i < rows; i++)
        for (j = 0; j < cols; j++)
            t += arr[i][j];

    return t;
}
